Field
Embodiments generally relate to the field of microarrays used for detecting and analyzing molecules of interest, such as biological materials.
Description of the Related Art
The detection of specific nucleic acids is an important tool for diagnostic medicine and molecular biology research. Gene probe assays currently play roles in identifying infectious organisms such as bacteria and viruses, in probing the expression of normal and mutant genes and identifying mutant genes such as oncogenes, in typing tissue for compatibility preceding tissue transplantation, in matching tissue or blood samples for forensic medicine, and for exploring homology among genes from different species. Recent advances include the fabrication of biomedical devices, such as microarrays, with gene probes incorporated therein.
Microarrays can be engineered to include probes for nucleotide sequences present in genes in humans and other organisms. In certain applications, for example, individual DNA and RNA biological probes may be attached at small locations in a geometric grid (or randomly) on a microarray support. A test sample, such as from a known person or organism, may be exposed to the grid, such that complimentary genes of fragments hybridize to probes at the individual sites in the array. The array can then be examined by scanning specific frequencies of light over the sites to identify which genes or fragments in the sample are present, by fluorescence of the sites at which genes or fragments hybridized.
In the fabrication of these biomedical devices, biofunctionalizing materials can be used in positioning and immobilizing the gene probes (also referred to as “probe adherence”). Biofunctionalizing material, when in a liquid state, often needs to be deposited into patterned regions (e.g., vias or wells). Liquid films of the biofunctionalizing material are generally deposited in a blanket fashion. Once deposited, a subsequent removal/clean step, such as chemical mechanical polishing (CMP), is needed to remove the material from the interstitial areas in between the patterned regions.
However, there are a number of difficulties in probe adherence that should be addressed. As stated above, hydrogel is used in current devices to assist in probe adherence. However, the hydrogel has limited adherence to the bottom of the well. As such, the bottom of the well must be treated to increase hydrogel adherence, such as by using a silanization process. However, the silanization process is imperfect and adherence of the hydrogel is incomplete. Further, the hydrogel is generally deposited over the entire substrate with a portion of the hydrogel being delivered into the wells. The remaining hydrogel must be removed. Currently a standard CMP process is used to remove the hydrogel, which increases processing time and can damage the substrate.
Therefore, a there is a need for improvements in probe adherence in biomedical devices.